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Engineered Landfill
Landfill is always the last option for the disposal of waste. All of our landfill sites operate to the highest environmental standards and are subject to strict regulation and monitoring. Using power generating plants, Yorwaste harnesses the gases emitted from landfill to generate almost 10MW of renewable and clean energy that is fed directly back into the National Grid. Communities living near to our landfill sites are consulted and informed about the work of the sites, and through Yorventure, an independent not-for-profit Environmental Body, grants are distributed to community and environmental projects through the Landfill Communities Fund with landfill tax credits generated by Yorwaste. A landfill is constructed to include containment systems and structure designed to protect the environment. These measures include lining systems, gas pipes, rainwater collection control and monitoring boreholes.
Waste in landfills is naturally broken down by microbes under anaerobic (absence of oxygen) conditions. This decomposition, combined with rainwater filtering through the landfill, results in the production of leachate (liquid) and gas. Leachate is contained by the lining system of the landfill and pumped and extracted through pipes which deposit it into the bio-treatment lagoons.
The gas produced by the landfill is predominantly a mixture of carbon dioxide and methane. This gas is extracted through a series of pipes, directed to our on-site energy generation plant, where it is converted into electricity and exported to the National Grid. Monitoring boreholes across the site regularly monitor the levels of leachate and gas in and around the landfill and ensure that the containment systems are working effectively. The leachate collection system is controlled by a sophisticated computer system that contacts remote points across the site gathering leachate data and setting a pumping time for the pumps that are required to run. The control system allows us to pump the leachate across the sites into the treatment lagoons for final processing.
When the landfill reaches maximum capacity it is capped, covered with a final layer of cover material, clay and vegetation. This final layer forms a barrier keeping odours in and rainwater out, as well as providing a suitable surface for future use in recreation and light cultivation.
Electricity production from the landfill gas will continue for many years after the landfill has been completed. Containment, control and processing systems stay in operation for up to 25 years after closure, ensuring the landfill’s stability and protection of the environment.